The use of enzymes to enhance the washing and cleaning performance of washing and cleaning agents has been established in the existing art for decades. Because of their immediate cleaning action, hydrolytic enzymes in particular, such as proteases, amylases, or lipases, are a constituent of numerous textile or tableware cleaning agents.
Proteases, in particular serine proteases, among which the subtilases are also categorized according to the present invention, serve to break down protein-containing stains on the items being cleaned. Among the washing- and cleaning-agent proteases, subtilases occupy an outstanding position because of their favorable enzymatic properties such as stability or optimum pH. From the enzyme class of the amylases, the α-amylases in particular are widely used. α-Amylases (E.C. 3.2.1.1) hydrolyze internal α-1,4-glycosidic bonds of starch and starch-like polymers.
The cleaning action of the enzymes used in washing and cleaning agents, which is critical for the end user, is determined not only by the enzyme structure, but also to a substantial extent by the manner in which these enzymes are packaged, and their stabilization in terms of environmental influences.
Enzymes having washing and cleaning activity are packaged in both solid and liquid form. The group of the solid enzyme preparations includes, in particular, the enzyme granulates made up of multiple ingredients, which in turn are preferably incorporated into solid washing and cleaning agents. Liquid or gelled washing and cleaning agents, in contrast thereto, often contain liquid enzyme preparations; these, unlike the enzyme granulates, are much less protected from external influences.
A number of different protective actions have been proposed for increasing the stability of such enzyme-containing liquid washing or cleaning agents. German patent application DE 2 038 103 (Henkel), for example, teaches the stabilization of enzyme-containing dishwashing agents using saccharides, while European patent EP 646 170 B1 (Proctor & Gamble) discloses propylene glycol for enzyme stabilization in liquid cleaning agents.
Polyols, in particular glycerol and 1,2-propylene glycol, are described in the existing art as reversible protease inhibitors. A corresponding technical disclosure is found, for example, in international application WO 02/08398 A2 (Genencor).
The stabilization of enzymes in aqueous cleaning agents by means of calcium formate, calcium acetate, or calcium propionate is described by U.S. Pat. No. 4,318,818 (Procter & Gamble).
The use of lactic acid salts for enzyme stabilization is described by US patent application US 2002/128588 (Dow Chemical).
A second group of known stabilizers is constituted by borax, boric acids, boronic acids, or salts or esters thereof. Principally to be mentioned among them are derivatives having aromatic groups, for example ortho-, meta-, or para-substituted phenylboronic acids, in particular 4-formylphenylboronic acid (4-FPBA), resp. the salts or esters of the aforesaid compounds. The latter compounds are disclosed as enzyme stabilizers, for example, in international patent application WO 96/41859 A1 (Novo Nordisk). Boric acids and boric acid derivatives, for example, nevertheless often have the disadvantage that they form undesired secondary products with other ingredients of a composition, in particular washing-resp. cleaning-agent ingredients, so that they are no longer available in the relevant agents for the desired cleaning purpose, or even remain behind as contamination on the items being washed. In addition, boric acids resp. borates are considered disadvantageous from an environmental standpoint.
The methods hitherto discovered and described in the existing art for stabilizing enzymes are not usable in every cleaning-agent formulation, depending on the chemical nature of the stabilizers, and cannot always be sufficient in terms of their stabilizing action. Accordingly, it is desirable to furnish an improved stabilizing agent for enzymes, as well as an enzyme-containing cleaning agent having elevated enzyme stability. It has been found that liquid, aqueous amylase preparations can, surprisingly, be stabilized by the addition of calcium lactate.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.